Recent research has demonstrated that reduced insulin-stimulated glucose metabolism in skeletal muscle (insulin resistance) and hyperinsulinism are common features in widespread diseases such as essential hypertension, android obesity, non-insulin dependent diabetes mellitus, dyslipidemia (in the form of raised serum triglyceride and reduced serum high-density lipoprotein (HDL) cholesterol) and arteriosclerosis. Simultaneously, investigations in a comprehensive group of healthy middle-aged men have revealed insulin resistance in one fourth. On the basis of these observations, a working hypothesis is suggested which postulates that genetic abnormalities in one or more of the candidate genes in the modes of action of insulin occur in a great proportion of the population. These may result in insulin resistance (primary genetic insulin resistance). Primary insulin resistance may be potentiated by a series of circumstances such as ageing, high-fat diet, lack of physical activity, hormonal and metabolic abnormalities or drugs (secondary insulin resistance). As a consequence of the reduced effect of insulin on muscle tissue, compensatory hyperinsulinism develops. Depending on the remaining vulnerability of the individual the hyperinsulinism is presumed to result in development of one or more phenotypes. For example if the beta-cells of the pancreas are unable to secrete sufficient insulin to compensate the insulin resistance on account of genetic defects, glucose intolerance will develop. In a similar manner, hyperinsulinism in insulin-resistant individuals who are predisposed to essential hypertension is presumed to reveal genetic defects in the blood pressure regulating mechanisms and thus contribute to development of the disease.(ABSTRACT TRUNCATED AT 250 WORDS)